A number of tornadoes slammed central Iowa on Thursday, causing significant damage.

In Marshalltown, several buildings and an historic courthouse were damaged in the main business district. Video from Twitter user @b_hernandez21s shows the twister toppling the clock tower atop the courthouse:

Ten people were injured as brick walls collapsed into the streets, roofs were blown off buildings and the cupola of the historic courthouse tumbled to the ground.

More than 5,800 customers remained without power in Marshalltown early Friday, and natural gas service has been shut down in part of the city, according to Alliant Energy. The utility said crews have been dispatched to repair damage and assess which areas can have gas service safely restored.

The storms even surprised weather forecasters when they hit the region Thursday afternoon, causing extensive damage to a manufacturing plant and prompting the evacuation of a hospital. The National Weather Service said Friday that at least five tornadoes touched down.

Marshalltown, a city of 27,000 people about 50 miles northeast of Des Moines, appeared to have been hit the hardest.

The main hospital in Marshalltown was damaged and all 40 patients at UnityPoint Health were being transferred to the health system's larger hospital in Waterloo and one in Grundy Center, spokeswoman Amy Varcoe said. The emergency room in the smaller Marshalltown hospital remained open to treat patients, Varcoe said. Ten people hurt in the storm had been treated, she said.

Stephanie Moz said she, her husband and 2-month-old baby were in the downtown Marshalltown clothing store she owns when tornado sirens went off. She said the family sought shelter in the building's basement and heard "cracking and booms and explosions" as the tornado passed.

The storm broke out a window, ruining clothing and hats on display there, and destroyed her husband's vehicle. But she said she's relieved.

"We went through a tornado and survived," Moz said. "I'm happy."

Some buildings at the Iowa Veterans Home in Marshalltown sustained roof damage, but no residents or staffers were injured at the facility that houses nearly 500 people, according to Timon Oujiri, the facility's commandant. He said the facility lost power but was chugging along Friday on generators.

On Thursday, National Weather Service meteorologist Rod Donavon said two primary storms spawned the series of tornadoes. One developed in the Marshalltown area, while the other started east of Des Moines and traveled through Bondurant and into Pella, about 40 miles (64 kilometers) southeast of Des Moines.

The tornado in Pella hit the agricultural machinery maker Vermeer Manufacturing, scattering huge sheets of metal through a parking lot and leaving one building with a gaping hole. People were still working at the plant at the time.

Seven people injured at the plant were taken to Pella Regional Health Center, hospital spokeswoman Billie Rhamy said. They all were released after being treated for their minor injuries, Rhamy said.

Officials said Vermeer was hosting 500 customers for an appreciation day when the weather hit. The governor credited the company's security team with moving them all to safety.

Forecasting models produced Thursday morning showed only a slight chance of strong thunderstorms later in the day, said Alex Krull, a meteorologist with the National Weather Service in Des Moines.

"It didn't look like tornadic supercells were possible," Krull said. "If anything, we were expecting we could get some large hail, if strong storms developed."

Iowa state Rep. Mark Smith, who lives in Marshalltown, told Des Moines station KCCI-TV that the area likely will be declared a disaster area. Smith said much of downtown was damaged. He said his house and neighborhood were spared, but surrounding homes were hit.

"There are houses with windows out, houses without roofs," he said. "It's just an absolute mess."